Well i dont know about angels, but i believe there are forces out there that try to communicate. Once when i was in the 7th grade, I couldnt sleep. At first i thought it was the power cut. But the fan was running. As i was getting back into bed and just before i tucked myself in i heard a voice saying "Give up".
I freaked out. I imediately turned on the lights and there was no one. But i know it was not my imagination. I checked under my bed, my closet, but nothing. There wast anyone there playing any pranks.... True story.